Fully boxed frame? 9 crossmembers?

Heretic · August 15th, 2005 01:35 AM

We're thinking of retiring our old Tamarraw FX. We are contemplating on getting an SUV that would tolerate the roads of Pilaoan, La Union. We narrowed down our choices to the Fortuner 2.5 diesel and Sorento 2.5 diesel.

I was searching for reviews when I read this about the Kia Sorento:

"The hardware is robust - fully boxed frame with 9 crossmembers, a coil-spring control-arm front and live-axle rear suspension, and vented disks all around - all which suggest high towing capacity.

What does a fully boxed frame and 9 crossmembers mean?

**Bry** · August 15th, 2005 01:48 AM

I don't know, haha.

But between your two choices, I'd choose the Fortuner. Downside lang nyan is kung ngayon ka lang magpapa-reserve, mahaba na din ang pila.

Heretic · August 15th, 2005 01:57 AM

My first choice was originally the Fortuner as well, but after reading the Kia's positive reviews in America and Europe, I'm beginning to have second thoughts about it. Add to that the more powerful, stat-wise at least, engine of the Sorento's 2.5 diesel compared to the Fortuner's 2.5 diesel.

**Bry** · August 15th, 2005 02:12 AM

Yeah, medyo underpowered nga yung 2.5, that's why I'm busy looking/asking around for possible engine modifications.

**wildthing** · August 15th, 2005 06:47 AM

wow from tamaraw fx to an SUV!

A boxed frame with 9 crossmember simply means that the chassis won't "twist" and is very rigid even if the engine excerts large amount of torque to turn the wheels.

Imagine a 9second drag race car for example, due to the sudden surge of power from the engine na biglang ni-rev, the turning/twisting motion of the engine will give a powerfull pressure para mag-twist din yung buong sasakyan. Kung rigid ang chasis, ikacounter nito yung twisting motion para hindi magwarp ang buong car.

Ganun din sa 4x4 na nabalaho or trapped in a pit. The lakas ng torque to turn a stucked wheel or SUV would be so powerfull that without a boxed frame with 9 crossmember controlling it, the chasis might twist and warp too.

HTH

**wildthing** · August 15th, 2005 06:49 AM

BTW I'm not a KIA fan...I will still go for a Toyota Fortuner.

**mbt** · August 15th, 2005 07:59 AM

fully boxed frame... this means that the cross section of the frame is shaped like [] . understand that the frame pieces are not solid beams of steel (would be too heavy). the whole length of the frame (from nose to tail) could be box-section; some frames are boxed only at certain parts (like at the front only)

this is opposed to C-shaped frame members... which has a cross section shaped like [ .

obviously, the fully-boxed frame part will be potentially much more rigid than the C-sections.

this has implications for frame rigidity, which is important for on-road handling, on-road ride and towing capability. however, it doesn't mean that C-section frames are weaklings.

nine crossmembers means that nine beams brace the frame rails together:

---------------
I I I I I I I I I
---------------

it would be potentially much more rigid than if it had only say, four crossmembers

in practice though, just because the spec sheet says so-and-so vehicle has a fully-boxed frame and a dozen crossmembers doesn't mean that it will necessarily have great handling and rigidity. just as having coil springs all around doesn't mean that it will necessarily have a comfy ride. I'd base a purchasing decision more on a test drive and test reports rather than a spec sheet.

**OTEP** · August 15th, 2005 08:16 AM

Having a fully boxed frame means you have a more rigid platform to place the body and a more stable mount for the suspension. MBT, got it right. A fully boxed chassis will have []-shaped frames instead of C-shaped ones.

Boxed frames will take more abuse as they are more rigid. However they are heavier and more expensive than regular frames.

Ford has just stared to use boxed frames on its latest F-150's. Some vehicles still continue to use C-shaped frames. Pajeros have been fully boxed since 1984.